The present invention relates to a method of selecting a group of optimum pneumatic devices that satisfy conditions specified by a user to construct a pneumatic system.
To construct a user-specified pneumatic system (i.e. a terminal system including components provided between a selector valve and an air cylinder inclusive), a slide rule for designing a pneumatic system was devised [see Japanese Patent Application Post-Examination Publication No. 53-21320 (1978)]. The slide rule has a fixed piece and a sliding piece on each of the obverse and reverse sides thereof. The fixed and sliding pieces are marked with associated scales so as to satisfy an equation for calculating a stroke time of a double acting cylinder, an equation for calculating an output of the cylinder, an equation for calculating an air consumption in the cylinder and piping, and other equations. The slide rule enables various data necessary for system design to be calculated rapidly by jointly using a cursor operation. To select a group of optimum pneumatic devices, the conventional practice is to perform an approximative simple calculation with the above-described slide rule because it has heretofore been impossible to perform an accurate dynamic characteristic simulation. Therefore, the probability that the results of the device selection will meet the requirements is considerably low. Thus, it has heretofore been impossible to construct a desired system with a group of smallest devices and to realize a minimal energy consumption and a minimal cost.
At present, it is demanded to develop a method of rapidly selecting a group of optimum devices that satisfy user-specified conditions by using a calculating method of high accuracy and high reliability. In the device selection, it is necessary to satisfy the following conditions 1 to 4:
1 Load condition [the selected system should satisfy a mechanical condition necessary for the system to be capable of satisfactorily operating in compliance with input conditions for the specified operating unit (pneumatic actuator), e.g. load mass, thrust, use application, and supply air pressure].
2 Speed condition [the selected system should operate so that an output member of the pneumatic actuator (e.g. a cylinder piston) can reach the stroke end within the specified total stroke time].
3 Strength condition [the selected system should satisfy the specified load condition and the pneumatic actuator should not be buckled, deformed or broken].
4 Connecting condition [the devices constituting the selected system should normally be connectable to each other].